A similar type of valve adjusting device is known in principal from DE-OS 30 24 109 corresponding to U.S. Pat. No. 4,455,543 (Pischinger et al).
This known device shows a gas exchange valve for an internal combustion engine, the stem of which is joined to the valve disk and has an anchor (or armature) plate which is alternatingly attracted to two opposed actuating solenoids, causing the valve to open or close. Pischinger also discloses the use of a distance spacer and a magnet cover (collectively known in the art as a "casing") which function to affix the tapped winding coils or solenoids and the bias coil within the cylinder head.
Modern day internal combustion engines have made great strides in valve design. The improved valve mechanisms have resulted in improved power output and fuel efficiency, and have also reduced emissions. This in large part is due to improvements in valve timing through the use of solenoid and spring-biased valve actuator assemblies. The prior art methods for improving gas exchange valve switching behavior have been primarily directed to ensuring reliable switching behavior by improving valve stem alignment within the actuator assembly. While this is a starting point for improving valve switching behavior, there is still a need for increasing the speed of the fast switching time behavior of the anchor plate to ensure precise position changes, and to keep up with the interval demands that are placed on gas exchange valves by newer engine designs under normal operating RPM ranges.
One method for accomplishing this is by increasing the magnetic force associated with each electromagnet in order to attract the reciprocating anchor plate. However, this also requires the use of stronger springs in order to compensate for the increased lag time associated with a stronger decaying electromagnetic force upon deenergization of an associated solenoid. This is not a preferred way of achieving faster switching behavior as larger magnetic cores and springs defeat the purpose of designing small and conveniently sized actuator assemblies. Moreover, the reliability of the reciprocating movement of the anchor plate must also be assured. Unduly powerful electromagnetic forces will tend to result in undesirable switching behavior as the associated spring members become fatigued and weakened over long operating periods.
Thus, there is a definite need in the art to improve the speed of fast switching time behavior of gas exchange valves whereby such improvements make optimal use of readily available components associated with current state of the art valve actuator designs.